The laminated, blow-molded containers comprising a synthetic-resin outer layer forming an outer shell of a fixed shape and an inner layer forming an inner bag to be laminated with this outer layer in a peelable manner, i.e., the so-called easy-to-delaminate bottles, are known. Patent document D1 describes an invention regarding a process and the equipment for punch-cutting one or more air intake holes in a portion of the outer layer in the neck to take in outside air.
FIG. 9 is an explanatory diagram showing schematically the process for forming an air intake hole. This diagram corresponds to FIG. 2 of the patent document D1 and shows a laminated, blow-molded container 1 along with a punch-cutting machine 30. The container 1 is an easy-to-delaminate bottle comprising a neck 2, a shoulder 3, and a body 4 and having the outer layer 11 laminated with the inner layer 12. The punch-cutting machine 30 mainly comprises a stationary member 31 and a cutting member 40 shown by a hatched area in the vertical section of FIG. 9.
The stationary member 31 comprises a support rod 34 hanging downward from a support member 32 and a cutter stop 36 disposed at a lower end portion of this support rod 34. The cutting member 40 comprises a sliding member 41, which is supported in a manner slidable from side to side by a support shaft 33 disposed horizontally and fitted to the support member 32, a cutter holder 42 hanging downward from this sliding member 41, and a punch-cutter 43 disposed at a lower end portion of the cutter holder 42 so that the punch-cutter 43 is opposed to the cutter stop 36 of the stationary member 31.
The punch-cutter 43 has a cylindrical blade 44 at the tip and a through-hole 46 to take out a cut piece 11a. When a driving means (not shown) is used to move the sliding member 41 to the left (in the X direction in FIG. 9) along the support shaft 33, the punch-cutter 43 also moves until the front face of a bolt 37 bumps into the support rod 34. At that time, the cylindrical blade 44 presses the inner layer 12 of the neck 2 of the container 1 against an opposed surface 36a of the cutter stop 36. Then, the blade 44 cuts into the outer layer 11 of the neck 2 of the container 1 forcibly, and cuts out a piece of the outer layer 11 while leaving the inner layer 12 intact, thus forming one or more air intake holes to take outside air into the interspace between the inner layer 12 and the outer layer 11. The air intake hole can be formed solely in the outer layer 11 by adjusting the bolt 37 to set a gap, t, between the blade edge of the cylindrical blade 44 of the punch-cutter 43 and the opposed surface 36a, at a length equivalent to the thickness of the inner layer 12.
FIG. 10 is a vertical section showing a state of lamination of the outer layer 11 and the inner layer 12 near an air intake hole 14 that has been formed as described above. After blow molding, the easy-to-delaminate bottles of this kind have the inner layer 12 and the outer layer 11 that should be peelable from each other, but in fact are in tight contact in many cases. Therefore, in some of the dispensing container products utilizing the easy-to-delaminate bottles of this kind, it is often difficult, after a content fluid has been dispensed, to utilize a pressure drop inside the bottle so as to take outside air smoothly into the interspace between the outer layer 11 and the inner layer 12 through one or more air intake holes 14. After the air intake hole or holes 14 has/have been formed, a vacuum pump and the like are used in many cases to suck air through the neck 2 in order to put the bottle inside forcibly under a reduced pressure condition. This causes the outer layer 11 and the inner layer 12 to be peeled from each other, and tentatively releases the tight contact of these layers over the entire region. Thereafter, air is blown through the neck 2 to bring the outer layer 11 and the inner layer 12 back to a laminated state.